Method of constructing a continuous pipeline



METHOD OF CONSTRUCTING A CONTINUOUS PIPELINE Original Filed June 15,1961 BY 61. 04 65 A 0K? United States Patent This application is adivision of application Serial No.

. 117,304, filed June 15, 1961, now abandoned.

This invention relates to the production of coated pipes suitablyconditioned for end-to-end welding into a pipe line. Of particularconcern is the production of pipes which are coated, except for smallexterior outside areas, adjacent each end.

In the manufacture of coated pipes and their assembly into pipe lines,there arises the problem of providing peripheral uncoated areas adjacenteach end of each pipe having the base material of the pipe free of allcoating material, corrosion, or dirt which might contribute to forminginferior joints connecting adjacent pipes. Clean welding surfaces arenecessary so as to avoid the inclusion of foreign matter in the weldedjoints and to avoid the production of fumes which are unpleasant andoften noxious to workmen.

By conventional procedure, the entire outer surface of each pipe iscoated and then the coating is peeled along a few inches of the lengthof the pipe as measured from each end to expose the base material of thepipe. By this practice, the base material is maintained free of dirt andcorrosion until used in constructing a pipe line.

The common practice is to manually strip or scrape the coating from thebase material just before incorporation of the pipe into a line and tothereby expend considerable labor and' time in preparing the pipe for aline construction operation, such as welding. As a practical matter,complete cleanliness of the base material is difl-lcult to obtain underfield conditions.

Hence, an important object of this invention is to provide a method ofconstructing completely coated pipes a coated portion of a pipe. Assuccessive pipes are welded together, or after the entire pipeline isassembled, each one of the second mentioned sleeves may be centered overa Weld joint with its ends overlapping coated areas of the pipesadjacent the joint and shrunk into stretched relation with the pipelineby the application of heat.

In the drawing in respect to which this invention is described:

. FIG. 1 is a fragmentary longitudinal elevation in sectionillustrating-a pipe with a heat shrinkablesleeve supported on the endportion of the pipe.

FIG. 2 is an end view of the pipe and sleeve shown in FIG. 1 with thepipe supported on rollers and the sleeve surrounded by a heating device.

FIG. 3 is a fragmentary longitudinal elevation in section of the pipeand sleeve of FIG. 1- showing the sleeve shrunken to a tightly stretchedcondition about the pipe.

FIG. 4 is a fragmentary longitudinal elevation in section showing thepipe and sleeve of-FIG. 3 after receiving a layer of coating material.

FIG. 5 is a fragmentary longitudinal elevation, partially in section,illustrating a step in the removal of the sleeve of the coated pipe asshown in FIG. 4.

FIG. 6 is a fragmentary longitudinal elevation in section of the coatedpipe of FIGS. 4 and 5 with the sleeve removed.

FIG. 7 is a fragmentary perspective view of two pipes similar to the oneshown in FIG. 6 welded together and one of the pipes carrying a looselyfitting sleeve over the coated portion thereon.

FIG. 8 is a fragmentary elevation of the pipe line shown in FIG. 7 withthe sleeve in centered position over the of which the base materialforming the exterior wall areas weld-joint.

FIG. 9 is a fragmentary elevation of the pipeline of FIGS. 7 and 8 withthe sleeve shrunken into tightly-fitting relation with uncoated areasadjacentthe weld-joint and marginal coated areas adjacent the uncoatedareas.

FIGS. 1 to 6 depicta pipe 5 and a sleeve 6 utilized in this invention tomaintain the end portion 8 of the pipe free from any foreign materialdetrimental to its installation in a pipeline through any ordinaryprocessing, transportation, or storage condition. An initial step inpreparing a pipe in accordance with the invention is to place the sleeve6 over the end portion 8 in loosely fitting relationship, as shown inFIGS. 1 and 2. The sleeve 6 is obtained as ashort length of anextrudedplastic tubular These objects are in general achieved by providing pipeswhich are completely coated, and may remain so until the instant ofWelding, but are momentarily adaptable for welding by removal of asleeve of heat-shrinkable material stretched tightly about the basematerial of the pipe forming each end portion thereof.

In a preferred embodiment, the sleeve comprises a thin-walledthermoplastic material, such as polymerization product predominately ofa vinyl halide, substantially nonadherent with respect to the basic pinematerial. The sleeve is useful for receiving any coating materialincidentally spread thereon to obtain satisfactory coating of thesurface of the pipe not covered by the sleeve and for protecting thesleeve between the time of coating and the time of pipe-lineconstruction.

, In accordance with this invention, pipes coated in the I producthaving an internal periphery sufficiently larger than the externalperiphery of the pipe to enable easy application. A satisfactorycomposition of which the sleeve 6 consists in practicing this inventionis a copolymer of parts vinyl chloride and 20 parts vinyl acetate mixedwith a plasticizer, diisodecyl phthalate in to 30 copolymer toplasticizer ratio. The proportions just expressed are' typical butnon-critical with respect to others that may be employed.

The next step isillustrated in FIG. 2 in which heat is applied in auniform manner to the external surface of the sleeve to reach atemperature short of the melting. temperature of the sleeve material toinduce shrinking. Illustrative of the heating devices that may be usedis the shroud 10 with eight lighting fixtures 11 projecting therethroughand supporting bulbs 12. The device should be capable, for example, ofheating sleeves of vinyl-type polymerization products to 225 -250 F. Thepipe 5 is supported by means, such as a plurality of rollers similar tothe roller 14 along portions of the pipe inwardly of its length from thesleeve 6;. The pipe is advanced longitudinally through the heating.device by means such as the motor and gear reduction unit 15 connectedwith the roller 14 by a bevel gear and sprocket transmission system, asshown.

The sleeve 6 may comprise any one of the thermoplastic heat-shrinkablepolymerization products wellknown to the plastic art. Well-known forthis property are vinyl resins of various types and particularly thosecontaining vinyl halide and, more particularly, copolymers of vinylchloride and vinyl acetate in which the vinyl chloride predominates. Assome of the vinyl type resins, for example, unplasticized polyvinylchloride and 70-30 vinyl chloride-vinyl acetate copolymer are somewhatstifi at room temperatures such resins may be modified with conventionalplasticizers to provide such flexibility as will render them moreadaptable for use in the present invention. These plastic compositionsmay be modified in any way desired as long as their capacity to shrinkis not impaired. The heat shrinkable vinyl resins are also characterizedby a lack of adhesion to metal at sub-fusion temperatures. Modifiers arepreferably avoided which substantially affect that property.

After the sleeve 6 is shrunken tightly about the pipe, as shown in FIG.3, the pipe is ready for application of the coating material normallyapplied to pipe for resistance against severe corrosion conditions. Inpractice, the pipe is transferred longitudinally from the heatingstation of FIG. 2 into a conventional coating machine, e.g., the typeillustrated in iWeland et al. 1,862,837, or a conventional coating andwrapping machine as illustrated in Brend Patent No. 2,368,742. Thecoating step may also be carried out by flame gun application of organicplastics in equipment well-known to the coating art, or by applicationof heat by any of the well-known procedures of spraying, spreading, ordipping techniques. The coating 15 may overlap the sleeve 6 as shown andto any extent desired in order to achieve uniform thickness of thecoating on the areas of the pipe not covered by the sleeve 6.

After the coating step, preferably after the coating 15 has hardened ordried, the sleeve or sleeves 6 may be removed from the pipe at any timeby merely cutting through thecoating, as shown in FIG. 5, along thecontour line 17 occurring at the coated end of the sleeve. On account ofthe tightly-stretched condition of the sleeve, cutting thereof in thelongitudinal direction of the pipe facilitates removal.

Due to the choice of material constituting the sleeve, e.g., a vinylresin containing predominately vinyl chloride, the sleeve isnon-adherent with respect to the metallic surface of thepipe andseparates with ease, and leaves the surface of the pipe in the precisesurface condition it had when receiving the sleeve. Generally speaking,the sleeve of the pipe will not be removed until installation in apipeline in order to avoid any damage to the end portions of the pipenormally possible in handling, transit and storage. Forexample,protection is provided in the ordinary and frequent occasion wherein thepipe ends are thrust, into, or placed in contact with, the ground duringtheir distribution along a pipeline site several days before the pipesare welded into the pipeline.

The plastic material of the sleeves assures tightness against the pipe,resistance to abrasion, and imperviousness to atmospheric and soilcomponents.

FIGS. 7 to 9 illustrate the integration of coated pipes into anassembled, completely coated or covered pipeline as illustrated in FIG.9. To attain such assembly by welding the pipes together, it isnecessary to position jointcovering sleeves similar to a sleeve 20 onthe pipes prepared as shown in FIG. 6, in some manner that a sleeve 20will be available, as the pipeline is progressively constructed, tocover the exposed base pipe areas adjacent each welded joint. Thepreferable pactice is to install a sleeve 20 on the coated area of eachpipe before it is welded into the pipeline. The sleeve remains out ofproximity with the welding operation since any substantial heatingpreliminary to its positioning over the welded area would be detrimentalto its installation.

FIG. 7 illustrates two pipes 5, 5a united by a weld joint 22. Areas 24,24a are exposed metal surfaces of the pipe disposed between extremities25 and 26 of the coating of the two joined pipes. At this stage in theconstruction of the pipeline, it is highly important to provide againstaccess of atmosphere, soil solutions, condensation, etc., through pinholes or other openings inadvertently occurring through or adjacent thesleeve 20 after being shrunk into place. Accordingly, the areas 24 and24a are coated with a primer 19 (described below in greater detail)applied as by brushing, as shown in FIG. 7.

The sleeve 20 comprises a material which may be identical in compositionwith the sleeve 6 since similar reaction to heat and resistance tocorrosion and moisture permeation are required. However, whereasnonadhesion of the sleeve 6 for the pipe is desired, the sleeve 20 ispermanently attached and preferably bonded to the pipe 5. The sleeve20may occupy an out-of-way position on the coating 15, such as shown inFIG. 7 during and immediately after welding together of the pipes 21.Soon after the welding and priming operations, the sleeve 20 maybeshifted to the position shown in FIG. 8 wherein its end portions extendpast the coating edges 25 and 26 and overlap one or two inches of thecoating area 15 of each pipe. With careful timing, it is possible toutilize the heat stored in the pipe areas 24, 24a to bring aboutshrinkage of the sleeve 20 into the tightfitting stretched relationshipshown in FIG. 9. This figure illustrates that the sleeve 20 has shrunkento such an extent as to be formed in tight conformity with the exteriorsurface of the coating 15, 15a of each pipe and to the previouslyexposed areas 24, 24a of slightly less diameter than the coated area. Inthe event that heat stored in the pipeline was not utilized in themanner just described, portable heating devices may be employed. Onepreferred type is that which at least partly encircles the pipe anddischarges a heated, flameless, dry gas. Portable radiation type heatersof the general type illustrated in FIG. 2 may also be used. The primer19, applied prior to final positioning of the sleeve 20, is preferablyof a material which bonds firmly with the sleeve and base material orthe pipe,.particularly the latter, in order that corrosive action may.not spread from e.g., a chance point of exposure of the base materialsuch as that resulting from a pinhole in the sleeve 20.

One of the cheapest priming materials available is asphalt which must beeither heated or mixed with solvents to be readily applicable. Underservice conditions which warrant the expense ofan extremely firm bond ofthe sleeve 20 with the base material, adhesives may be used based uponcertain plastics that have an affinity .both for steel and the vinylchloride polymers and copolymers. Examples of plastic materialsproviding good vinyl-tometal bonding as the basic component of anadhesive are: (l) the epoxies (e.g., as derived from biphenol A andepichlorohydrin) and used in combination with a suitable cold-settingcuring agent such as an aliphatic amine;

(2) polyesters in combination with suitable cold-setting catalystswell-known to the art; and

(3) mixtures of resins, e.g., epoxy-polyamide mixtures. Theplastic-typeadhesives are provided preferably in viscosities varying from viscousliquid to paste-like consistency adapting them for field application bybrushing, spraying or troweling. Because of the undesirability ofintroducing any moisture under the highly moisture impervious sleeve 20,solution-type adhesive depending for their fluidity on organic solventsare preferred over emulsion-type adhesives, and those resin-formingmaterials that yield water as a condensation product during curing. Inview of the usual practice of coating and taping the exposed metal areasadjacent to a welded pipe joint, the foregoing discloses an extremelyadvantageous procedure with respect to time, labor and expense.Moreover, as minute air leaks following the lines of overlap in aspirally taped joint have in the past contributed substantially to jointcorrosion, the present invention assures the construction oftrouble-free joint coverings requiring less skill and care in theirpreparation.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation, and there is no intention ofexcluding such equivalents of the invention described or of the portionsthereof as fall within the scope of the claims.

What is claimed is:

1. A method of constructing a continuous pipeline of a plurality ofpipes comprising the steps of: providing thin-walled sleeves ofheat-shrinkable organic thermoplastic material which is substantiallynon-adherent with respect to material of the pipes; placing one of saidsleeves over a short length of each pipe contiguous with each end;heating the sleeves so placed to shrink them tightly about the endportions of the pipe; applying a coating material to the pipe betweensaid sleeves stretched thereon and to an extent overlapping saidsleeves; removing the sleeves from each pipe after the coating stepalong with coating material carried thereon; after the coating step,placing another sleeve of heat-shrinkable organic thermoplastic materialof length exceeding twice the length of one said exposed end portion andadapted to fit loosely around a portion of the pipe carrying saidcoating material around the coated portion of one of said pipes; weldingthe pipes in end-to-end relationship; placing said other sleeve car-References Cited by the Examiner UNITED STATES PATENTS 1,120,731 12/1814McIlroy. 2,027,962 1/ 1836 Currie. 2,118,073 5/ 1838 Dittmeyer 2,786,264 3/ 1957 Colombo 29-460 X 3,068,563 12/ 1962 Reverman 29-4583,138,861 6/1964 Gaido 29-475 WHITMORE A. WILTZ, Primary Examiner.

CHARLIE T. MOON, Examiner.

1. A METHOD OF CONSTRUCTING A CONTINUOUS PIPELINE OF A PLURALITY OFPIPES COMPRISING THE STEPS OF: PROVIDING THIN-WALLED SLEEVES OFHEAT-SHRINKABLE ORGANIC THERMOPLASTIC MATERIAL WHICH IS SUBSTANTIALLYNON-ADHERENT WITH RESPECT TO MATERIAL OF THE PIPES; PLACING ONE OF SAIDSLEEVES OVER A SHORT LENGTH OF EACH PIPE CONTIGUOUS WITH EACH END;HEATING THE SLEEVES SO PLACED TO SHRINK THEM TIGHTLY ABOUT THE ENDPORTIONS OF THE PIPE; APPLYING A COATING MATERIAL TO THE PIPE BETWEENSAID SLEEVES STRETCHED THEREON AND TO AN EXTENT OVERLAPPING SAID SLEEVE;REMOVING THE SLEEVES FROM EACH PIPE AFTER THE COATING STEP ALONG WITHCOATING MATERIAL CARRIED THEREON; AFTER THE COATING STEP, PLACINGANOTHER SLEEVE OF HEAT-SHRINKABLE ORGANIC THERMOPLASTIC MATERIAL OFLENGTH EXCEEDING TWICE THE LENGTH OF ONE SAID EXPOSED END PORTION ANDADAPTED TO FIT LOOSELY AROUND A PORTION OF THE PIPE CARRYING SAIDCOATING MATERIAL AROUND THE COATED PORTION OF ONE OF SAID PIPES; WELDINGTHE PIPES IN END-TO-END RELATIONSHIP; PLACING SAID OTHER SLEEVE CARRIEDON EACH PIPE OVER CONTIGUOUS UNCOATED PIPE END PORTIONS JOINED TOGETHERWITH THE SLEEVE OVERLAPPING THE COATED AREAS OF THE ADJACENT PAIR OFPIPES; AND APPLYING HEAT TO SAID SLEEVE PLACED OVER SAID CONTIGUOUS PIPEPORTIONS TO SHRINK THE SLEEVE THEREABOUT IN OVERLAPPING RELATION WITHSAID COATED AREAS.